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Re: [PATCH v3 1/2] xen/arm: Defer request_irq on secondary CPUs after local_irq_enable



Hi Henry,

On 07/05/2022 03:54, Henry Wang wrote:
With the enhanced ASSERT_ALLOC_CONTEXT, calling request_irq before
local_irq_enable on secondary cores will lead to

(XEN) Xen call trace:
(XEN) [<000000000021d86c>] alloc_xenheap_pages+0x74/0x194 (PC)
(XEN) [<000000000021d864>] alloc_xenheap_pages+0x6c/0x194 (LR)
(XEN) [<0000000000229e90>] xmalloc_tlsf.c#xmalloc_pool_get+0x1c/0x28
(XEN) [<000000000022a270>] xmem_pool_alloc+0x21c/0x448
(XEN) [<000000000022a8dc>] _xmalloc+0x8c/0x290
(XEN) [<000000000026b57c>] request_irq+0x40/0xb8
(XEN) [<0000000000272780>] init_timer_interrupt+0x74/0xcc
(XEN) [<000000000027212c>] start_secondary+0x1b4/0x238
(XEN) [<0000000084000200>] 0000000084000200
(XEN)
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 4:
(XEN) Assertion '!in_irq() && (local_irq_is_enabled() ||
num_online_cpus() <= 1)' failed at common/page_alloc.c:2212
(XEN) ****************************************

on systems without a big enough pool for xmalloc() to cater the
requested size.

Moving the call of request_irq() past local_irq_enable() on
secondary cores will make sure the assertion condition in
alloc_xenheap_pages(), i.e. !in_irq && local_irq_enabled() is
satisfied. It is also safe because the timer and GIC maintenance
interrupt will not be used until the CPU is fully online.

Reported-by: Wei Chen <Wei.Chen@xxxxxxx>
Suggested-by: Julien Grall <jgrall@xxxxxxxxxx>
Signed-off-by: Henry Wang <Henry.Wang@xxxxxxx>

Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>

Cheers,

--
Julien Grall



 


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